Siltation

Currently in Ireland there are extremely high siltation levels which are a cause for concern in respect to ecological habitats and fish spawning grounds as well as being sinks for phosphorous and other contaminants.

Based on evidence from the EPA and LAWPRO, poor practice in the drainage of rivers and land drainage have been identified as causing widespread environmental impacts.

The main sources of silt include

  • poor agricultural practices (e.g. drainage, lack of buffers etc.),
  • poor practices in channel maintenance,
  • poorly managed operations in legacy forests and
  • peat extraction / wind farms / quarrying

Suggested source control measures, such as catch crops and appropriate riparian margins, along with the development of land management plans.

Additional measures include planting of more trees, stopping access of cows and sheep into waterways and an increased protection of existing flood plains

Measures to tackle other significant issues will also deal with the issue of siltation.

Forestry and siltation

Site disturbing operations such as cultivation, road building and harvesting when combined with heavy rainfall pose a high risk of silt runoff into waterways. Great care is therefore required in carrying out these operations to ensure that the measures in the Forests and Water Guidelines are followed.  Silt has the effect of smothering streambeds and decreasing oxygen levels in the water which can greatly affect the fish and micro invertebrate life and even change the structure of the physical habitat.

Further information of forests and siltation can be accessed at:

An evaluation of the role of forests and forest practices in the eutrophication and sedimentation of receiving waters – literature review

SILTFLUX Literature Review – Environmental Protection Agency

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